The GainNode interface represents a change in volume. It is an AudioNode audio-processing module that causes a given gain to be applied to the input data before its propagation to the output. A GainNode always has exactly one input and one output, both with the same number of channels.

The gain is a unitless value, changing with time, that is multiplied to each corresponding sample of all input channels. If modified, the new gain is instantly applied, causing unaesthetic 'clicks' in the resulting audio. To prevent this from happening, never change the value directly but use the exponential interpolation methods on the AudioParam interface.